Lung cancer pic

Study objective: In lung cancer, vascular endothelial growth factor (VEGF) is an important cytokine and is correlated with tumor vessel density, malignant pleural effusions, and coagulation-fibrinolysis factors in vitro. We investigated the correlation between serum VEGF level and stage progression in lung cancer to study the predicted value of VEGF level. We also studied whether coagulation-fibrinolysis factors and Pa[O.sub.2] levels, which are also important factors for the prediction of the clinical course, are correlated with VEGF.

Methods: Forty-nine patients with lung cancer were investigated prospectively. VEGF levels of sera and malignant effusions, and plasma concentrations of coagulation-fibrinolysis factors were measured by enzyme-linked immunosorbent assay. We measured Pa[O.sub.2] levels in all patients at rest.

Results: Serum levels of VEGF were increased significantly according to stage progression. Additionally, plasma concentrations of D dimer, thrombin-antithrombin complex (TAT), and tissue plasminogen activator/plasminogen activator inhibitor type I complex were elevated significantly according to stage progression. The serum VEGF level had a significant positive correlation with the TAT and D dimer levels. Serum VEGF levels had a significant negative correlation with Pa[O.sub.2] levels. The incidence of cerebral vascular disorder was significantly higher in the patients with systemic hypoxemia than in those without (p [is less than] 0.05). Mean VEGF levels in malignant effusions in eight patients (five with pleural effusions, two with pericardial effusions, and one with both) were extremely high, especially in pericardia] effusions ([mean [+ or -] SD] pleural effusions, 531.9 [+ or -] 285.4 pg/mL; pericardial effusion, 3,071.6 [+ or -] 81.3 pg/mL).

Conclusion: We predict that in lung cancer, VEGF production and the abnormality of the coagulation-fibrinolysis system differ depending on the stage of progression of disease. Serum VEGF levels would be affected by Pa[O.sub.2] levels in lung cancer.

(CHEST 2000; 118:948-951)

Key words: cerebral vascular disorder; D dimer fragments; pericardial effusion; thrombin-antithrombin complex; tissue plasminogen activator/plasminogen activator inhibitor type I complex

Abbreviations: ELISA = enzyme-linked immunosorbent assay; PAI = plasminogen activator inhibitor type I; PIC = plasmin inhibitor complex; TAT = thrombin-antithrombin complex; tPA = tissue plasminogen activator; VEGF = vascular endothelial growth factor

Vascular endothelial growth factor (VEGF) is an important cytokine in cancer and is associated with increased tumor vessel density,[1]cancer metastasis,[2] cancer prognosis,[3] carcinomatous pleurisy,[4] and the coagulation-fibrinolysis system in vitro.[5] Systemic hypoxemia[6] induces elevations of serum VEGF levels, especially in patients with lung cancer.[7] However, little is known about the association of VEGF levels with stage progression of lung cancer, the association of VEGF and coagulation-fibrinolysis factors in lung cancer in vivo, and VEGF levels in malignant pericardial effusion associated with lung cancer. Also, evaluation of the coagulation-fibrinolysis system and control of pericardial effusions are important in predicting the clinical course of lung cancer patients. In this study, we investigated VEGF levels in the sera and malignant effusions of 49 lung cancer patients to determine whether this parameter might be used to evaluate disease progression. We also studied whether coagulation-fibrinolysis factors and Pa[O.sub.2] levels are correlated with VEGF in lung cancer patients.

MATERIALS AND METHODS

Patients

We prospectively investigated 49 consecutive lung cancer patients who were admitted to the Department of Respiratory Medicine (National Minami-Kyushu Hospital) from 1995 to 1999, including 39 men and 10 women whose mean ([+ or -] SD) age was 62.5 [+ or -] 12.3 years. We definitely excluded the patients with clinical or conventional laboratory evidence suggestive of intravascular coagulation abnormalities. We also excluded patients with diabetes mellitus, arteriosclerosis, and those receiving anticoagulant medication. For all patients, the diagnosis of lung cancer was confirmed by the histologic examinations of biopsy and cytologic specimens taken during bronchoscopic examinations. Staging was based on the new international staging system,[8] The staging procedure included the following: a clinical examination; standard chest radiography; CT scans of the chest, abdomen, and brain; bronchoscopy; liver ultrasonography; and bone scanning.

Adenocarcinoma was diaguosed in 28 patients, squamous cell carcinoma in 17 patients, and small cell lung cancer in 4 patients. Two patients were classified as having clinical stage I disease, 3 patients as having stage IIA disease, 13 patients as having stage IIB disease, 11 patients as having stage IIIA disease, 15 patients as having stage IIIB disease, and 5 patients as having stage IV disease. Eight patients had maliguant effusions (carcinomatous pleurisy, six patients; carcinomatous pericarditis, three patients; and both, one patient).

Clinical Study

We examined the Pa[O.sub.2] levels (measured with the patient breathing room air at rest) in all patients. The patients whose Pa[O.sub.2] levels were [is less than] 60 mm Hg were classified as having systemic hypoxemia (eight patients).

Measurement of Coagulation-Fibrinolysis Factors and VEGF

We measured plasma concentrations of D dimer fragments, thrombin-antithrombin complex (TAT), plasmin-[[Alpha].sub.2]-plasmin inhibitor complex (PIC), tissue plasminogen activator (tPA)/plasminogen activator inhibitor type I (PAI) complex, and serum VEGF in the 49 patients described above. Plasma D dimer concentrations were measured by enzyme-linked immunosorbent assay (ELISA) using a monoclonal antibody, which recognizes an antigenic determinant of D dimer, that was developed by Elms et al.[9] Plasma TAT levels were assayed using a solid-phase ELISA kit (Enzyguost-TAT; Behringwerke AG; Frankfurtain, Germany) by means of the sandwich principle and two different antibodies directed against human thrombin and antithrombin III.[10] Plasma concentrations of PIC were assayed by commercial ELISA kits (Teijin Ltd; Tokyo, Japan), employing an antiplasminogen antibody and a peroxidase-conjugated human anti-[[Alpha].sub.2]-plasmin inhibitor monoclonal antibody.[11,12] Plasma concentrations of tPA/PAI complex were measured by ELISA using a polyclonal antibody against PAI.[13] VEGF concentrations in serum and malignant effusions (ie, pleural and pericardial effusions) were measured in duplicate for each sample with a commercial ELISA kit (R&D Systems; Minneapolis, MN) that recognizes the soluble isoforms [VEGF.sub.121] and [VEGF.sub.165]. This assay is sensitive to 9 pg/mL (0.2 pmol) VEGF and does not cross-react with platelet-derived growth factor or other homologous cytokines. The optical density at 450 nm was measured on a plate reader (Titertek Multiskan MC; Flow Laboratories; Helsinki, Finland), and VEGF concentration was determined by linear regression from a standard curve and by computer software (Graph Pad; San Diego, CA) for analysis.

Statistical Analysis

All data were presented as mean [+ or -] SD. We used one-way factorial analysis of variance with a Bonferroni-Dunn test to determine the differences of VEGF levels and coagulation-fibrinolysis factors between the histologic patterns. A Spearman correlation coefficient by rank was used to measure differences in VEGF levels and coagulation-fibrinolysis factors between stages. We utilized Pearson's correlation coefficient to evaluate the correlations between VEGF and coagulation-fibrinolysis factors or Pa[O.sub.2] levels. The Mann-Whitney U test was utilized to measure the difference in VEGF levels between the patients with systemic hypoxemia and the patients without systemic hypoxemia. We used the [X.sub.2] test to evaluate the incidence of cerebral vascular disorder between patients with systemic hypoxemia and those without. A p value [is less than] 0.05 was considered significant.

RESULTS

The serum levels of VEGF, and the plasma concentrations of TAT, D dimer, and tPA/PAI complex were increased significantly according to the stage of progression of disease (Table 1). There were no significant differences between the histologic patterns (Table 2).

Table 1--Relationship Among VEGF, Coagulation-Fibrinolysis Factors, and the Clinical Stages of Disease(*)